| 1. |
- Broberg, Malin, 1989, et al.
(författare)
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CO2-induced changes in wheat grain composition: Meta-analysis and response functions
- 2017
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Ingår i: Agronomy. - : MDPI AG. - 2073-4395. ; 7:2
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Tidskriftsartikel (refereegranskat)abstract
- Elevated carbon dioxide (eCO2) stimulates wheat grain yield, but simultaneously reduces protein/nitrogen (N) concentration. Also, other essential nutrients are subject to change. This study is a synthesis of wheat experiments with eCO2, estimating the effects on N, minerals (B, Ca, Cd, Fe, K, Mg, Mn, Na, P, S, Zn), and starch. The analysis was performed by (i) deriving response functions to assess the gradual change in element concentration with increasing CO2 concentration, (ii) meta-analysis to test the average magnitude and significance of observed effects, and (iii) relating CO2 effects on minerals to effects on N and grain yield. Responses ranged from zero to strong negative effects of eCO2 on mineral concentration, with the largest reductions for the nutritionally important elements of N, Fe, S, Zn, and Mg. Together with the positive but small and non-significant effect on starch concentration, the large variation in effects suggests that CO2-induced responses cannot be explained only by a simple dilution model. To explain the observed pattern, uptake and transport mechanisms may have to be considered, along with the link of different elements to N uptake. Our study shows that eCO2 has a significant effect on wheat grain stoichiometry, with implications for human nutrition in a world of rising CO2.
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| 2. |
- Broberg, Malin, 1989
(författare)
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Effects of carbon dioxide and ozone on wheat crop yield and grain quality
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Atmospheric concentrations of carbon dioxide (CO2) and ozone (O3) have steadily increased since the industrial revolution. CO2 and O3 directly affect plant physiology, CO2 being an essential substrate for photosynthesis, while O3 is an oxidative agent causing damage to plant tissues. Due to strong concerns for future food security, effects on crop production are of particular interest. Wheat is a major food crop globally, being the second most important energy source. Accordingly, the overall aim of this thesis was to explore the general effects of elevated CO2 and O3 on wheat crops. CO2 and O3 impacts on wheat crops were systematically reviewed, using meta-analysis to estimate average effects, and deriving response functions to assess the effect size in relation to the concentration of either CO2 or O3. The underlying effects of O3 on grain nutrients was further explored in three experimental studies. Wheat yield increased by 25% on average under elevated CO2, but there was no further yield stimulation above 600 ppm. Elevated CO2 decreased grain protein concentration by 8% on average, but the effect was overestimated in pot grown plants. There was also a CO2-induced reduction in concentration of other grain nutrients, where CO2 effects on Fe and S were strongly correlated to the effects on protein but showed no relationship with grain yield stimulation. O3-induced reductions in wheat grain yield was shown to be mainly due to a decrease in grain mass, while grain number was only reduced to a small extent. Grain starch concentration was significantly reduced under O3 exposure, making starch yield the wheat yield variable most strongly affected by O3. O3 enhanced concentrations but strongly reduced the yield of important wheat grain nutrients such as protein, P, Mg, K, Ca, Zn and Mg. Both concentration and yield of Cd were reduced by O3. A comparison among our most important staple crops showed that O3 promoted a larger protein yield loss in soybean compared to rice and wheat. O3 reduced harvest index (HI) for most nutrient elements, but also for Cd, while the total element pool in aboveground biomass was unaffected (except for P). Consequently, the O3-induced reduction in grain element yield can be explained by lower remobilization rates rather than reduced uptake. There was a strong correlation of element HI when comparing sites and cultivars, indicating that it is primarily element specific and not strongly dependent on growing environment and genotypic differences. An experiment testing the interaction between O3, heat and drought stress showed that O3 effects on light saturated photosynthesis, grain mass and several grain nutrient concentrations were reduced under drought. Grain concentrations of protein, Ca and Zn were closely linked to grain yield regardless of O3, heat and drought stress. The significant impacts on wheat yield and grain quality suggest that there is a need to incorporate the influence of both CO2 and O3 in assessments of current and future global food security, but also account for the modifying effect of soil moisture.
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| 3. |
- Broberg, Malin, 1989, et al.
(författare)
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Effects of elevated CO2 on wheat yield: Non-linear response and relation to site productivity
- 2019
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Ingår i: Agronomy. - : MDPI AG. - 2073-4395. ; 9:5
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Tidskriftsartikel (refereegranskat)abstract
- © 2019 by the authors. Elevated carbon dioxide (eCO 2 ) is well known to stimulate plant photosynthesis and growth. Elevated carbon dioxide’s effects on crop yields are of particular interest due to concerns for future food security. We compiled experimental data where field-grown wheat (Triticum aestivum Linnaeus) was exposed to different CO 2 concentrations. Yield and yield components were analyzed by meta-analysis to estimate average effects, and response functions derived to assess effect size in relation to CO 2 concentration. Grain yield increased by 26% under eCO 2 (average ambient concentration of 372 ppm and elevated 605 ppm), mainly due to the increase in grain number. The response function for grain yield with CO 2 concentration strongly suggests a non-linear response, where yield stimulation levels off at ~600 ppm. This was supported by the meta-analysis, which did not indicate any significant difference in yield stimulation in wheat grown at 456–600 ppm compared to 601–750 ppm. Yield response to eCO 2 was independent of fumigation technique and rooting environment, but clearly related to site productivity, where relative CO 2 yield stimulation was stronger in low productive systems. The non-linear yield response, saturating at a relatively modest elevation of CO 2 , was of large importance for crop modelling and assessments of future food production under rising CO 2
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| 4. |
- Broberg, Malin, 1989, et al.
(författare)
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Effects of ozone, drought and heat stress on wheat yield and grain quality
- 2023
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Ingår i: Agriculture, Ecosystems & Environment. - 0167-8809. ; 352:15
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Tidskriftsartikel (refereegranskat)abstract
- Tropospheric ozone (O3) is a gaseous phytotoxic plant stressor known to reduce wheat (Triticum aestivum) crop yields at current concentrations. O3 is predicted to increase in many crop-growing regions, together with higher frequencies of heatwaves and droughts. In this study, wheat crops were exposed to two levels of O3 (ambient and ~70 ppb) in combination with ambient or elevated temperature (+8 ◦C) and two watering regimes (well-watered and 50% reduced water supply) during the grain-filling period. With this experimental setup, we assessed the interactive effects between O3, temperature and water supply on wheat yield and grain quality, and measured leaf gas exchange to explore the underlying mechanisms. Overall, O3, warming and drought all decreased grain yield and average grain mass but increased grain concentration of N and other nutrient elements. Increasing daytime O3 from 25 to 73 ppb resulted in a 25% yield reduction in treatments with ambient temperature and well-watered soil. Drought reduced the impact of O3 on light-saturated photosynthesis, grain mass, total aboveground biomass and grain concentrations of K, Ca, Mg, Mo. In contrast, concentrations of K and Ca increased to a larger extent when O3 stress was combined with elevated temperature. Grain concentrations of N, Ca and Zn were closely and negatively related to grain yield regardless of O3, heat and drought stress, likely explained by the reduction in grain filling period, with starch accumulation reduced to a larger extent than that of these elements. P, K, Mg, Mn, Mo concentrations were weakly related to grain yield, but were clearly altered by environmental stress. The modifying effect of water availability is crucial to include in assessments of O3 impacts on global food production in relation to climate change, considering effects on wheat yield variables and grain nutrient concentrations.
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| 5. |
- Broberg, Malin, 1989, et al.
(författare)
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Fertilizer efficiency in wheat is reduced by ozone pollution
- 2017
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 607-608, s. 876-880
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Tidskriftsartikel (refereegranskat)abstract
- Inefficient use of fertilizers by crops increases the risk of nutrient leaching from agro-ecosystems, resulting in economic loss and environmental contamination. We investigated how ground-level ozone affects the efficiency by which wheat used applied nitrogen (N) fertilizer to produce grain protein (NE P , N efficiency with respect to protein yield) and grain yield (NE Y , N efficiency with respect to grain yield) across a large number of open-top chamber field experiments. Our results show significant negative ozone effects on NE P and NE Y , both for a larger data set obtained from data mining (21 experiments, 70 treatments), and a subset of data for which stomatal ozone flux estimates were available (7 experiments, 22 treatments). For one experiment, we report new data on N content of different above-ground plant fractions as well as grain K and P content. Our analysis of the combined dataset demonstrates that the grain yield return for a certain investment in N fertilizer is reduced by ozone. Results from the experiment with more detailed data further show that translocation of accumulated N from straw and leaves to grains is significantly and negatively affected by ozone, and that ozone decreases fertilizer efficiency also for K and P. As a result of lower N fertilization efficiency, ozone causes a risk of increased N losses from agroecosystems, e.g. through nitrate leaching and nitrous oxide emissions, a hitherto neglected negative effect of ozone. This impact of ozone on the N cycle implies that society is facing a dilemma where it either (i) accepts increased N pollution and counteracts ozone-induced yield reductions by increasing fertilization or (ii) counteracts N pollution under elevated ozone by reducing fertilization, accepting further yield loss adding to the direct effect of ozone on yield.
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| 6. |
- Broberg, Malin, 1989, et al.
(författare)
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Harvest index and remobilization of 13 elements during wheat grain filling: Experiences from ozone experiments in China and Sweden
- 2021
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Ingår i: Field Crops Research. - : Elsevier BV. - 0378-4290. ; 271:15 September 2021
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Tidskriftsartikel (refereegranskat)abstract
- Wheat efficiently remobilize and allocate a large fraction of aboveground biomass and nutrients into their grains during maturation. This senescence process has been streamlined through crop breeding, which lead to increasing harvest index (HI) for biomass. With field data from two ozone exposure experiments, we derived HI for 13 elements, both nutrients and non-essential, to determine how efficiently they are allocated into the wheat grain in two different agro-ecological environments (Sweden and China) and under different ozone exposure regimes. Element HI ranged from 10 to 90 %, with highest rates for P, N and Zn (90 %, 80 % and 70 %, respectively), while HI was low for the non-mobile elements Ba, Sr and Ca (<10 %). HI for biomass was about 50 %, and the non-essential and toxic element Cd was in the same range (∼40 %). Overall element HI was very similar in Chinese and Swedish wheat cultivars. This was also the case when comparing the two Chinese genotypes. We conclude that element HI for wheat crops are highly element specific and not strongly dependent on site or cultivar. Ozone exposure significantly reduced HI for both macronutrients (Ca, K, Mg, N, P) and micronutrients (Cu, Mn, Mo, Zn), but also for Cd, while there was no ozone effect on the total aboveground pool for any element except P and Ba. Consequently, the reduction in grain element yield induced by elevated ozone, observed in previous studies, can be explained by lower remobilization rates rather than reduced total uptake. Our results provide new insights of nutrient use efficiency in wheat crops in general and under ozone exposure, which can be implemented in crop modelling and also useful for breeding strategies aiming to improve the nutritional value of food crops.
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| 7. |
- Broberg, Malin, 1989, et al.
(författare)
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Ozone effects on wheat grain quality - A summary
- 2015
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Ingår i: Environmental Pollution. - : Elsevier BV. - 0269-7491. ; 197, s. 203-213
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Tidskriftsartikel (refereegranskat)abstract
- We synthesized the effects of ozone on wheat quality based on 42 experiments performed in Asia, Europe and North America. Data were analysed using meta-analysis and by deriving response functions between observed effects and daytime ozone concentration. There was a strong negative effect on 1000- grain weight and weaker but significant negative effects on starch concentration and volume weight. For protein and several nutritionally important minerals (K, Mg, Ca, P, Zn, Mn, Cu) concentration was significantly increased, but yields were significantly decreased by ozone. For other minerals (Fe, S, Na) effects were not significant or results inconclusive. The concentration and yield of potentially toxic Cd were negatively affected by ozone. Some baking properties (Zeleny value, Hagberg falling number) were positively influenced by ozone. Effects were similar in different exposure systems and for spring and winter wheat. Ozone effects on quality should be considered in future assessments of food security/ safety.
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| 8. |
- Broberg, Malin, 1989, et al.
(författare)
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Ozone induced loss of seed protein accumulation is larger in soybean than in wheat and rice
- 2020
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Ingår i: Agronomy. - : MDPI AG. - 2073-4395. ; 10:3
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the effects of ozone (O3) on seed protein accumulation in soybean, rice, and wheat based on existing literature. We identified 30, 10, and 32 datasets meeting the requirements for soybean, rice, and wheat, respectively. Data for each crop were combined in response regressions for seed protein concentration, seed protein yield, and seed yield. Although seed yield in rice was less sensitive to O3 than in wheat, there was a significant positive effect of O3 on the seed protein concentration of the same magnitude in both crops. Soybean, an N-fixing high-protein crop, responded differently. Even though the effect on seed yield was similar to wheat, there was no indication of any effect of O3 on seed protein concentration in soybean. The negative influence of O3 on seed protein yield was statistically significant for soybean and wheat. The effect was larger for soybean (slope of response function: −0.58% per ppb O3) than for wheat (slope: −0.44% per ppb) and especially compared to rice (slope: −0.08% per ppb). The different response of protein concentration in soybean, likely to be associated with adverse O3 effects on N fixation, has large implications for global protein production because of the much higher absolute protein concentration in soybean.
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| 9. |
- Klingberg, Jenny, 1978, et al.
(författare)
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Influence of urban vegetation on air pollution and noise exposure – A case study in Gothenburg, Sweden
- 2017
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 599-600, s. 1728-1739
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Tidskriftsartikel (refereegranskat)abstract
- Air pollution levels (NO2, PAHs, O3) were investigated, before (BLE) and after (ALE) leaf emergence, in the urban landscape of Gothenburg, Sweden. The aims were to study the 1) spatial and temporal variation in pollution levels between urban green areas, 2) effect of urban vegetation on air pollution levels at the same distance from a major emission source (traffic route), 3) improvement of urban air quality in urban parks compared to adjacent sites near traffic, 4) correlation between air pollution and noise in a park. O3 varied little over the urban landscape. NO2 varied strongly and was higher in situations strongly influenced by traffic. Four PAH variables were included: total PAH, total particle-bound PAH, the quantitatively important gaseous phenanthrene and the highly toxic particle-bound benzo(a)pyrene. The variation of PAHs was similar to NO2, but for certain PAHs the difference between highly and less polluted sites was larger than for NO2. At a vegetated site, NO2 and particulate PAH levels were lower than at a non-vegetated site at a certain distance from a busy traffic route. This effect was significantly larger ALE compared to BLE for NO2, indicating green leaf area to be highly significant factor for air quality improvement. For particulate PAHs, the effect was similar BLE and ALE, indicating that tree bark and branches also could be an important factor in reducing air pollution. Parks represented considerably cleaner local environments (park effect), which is likely to be a consequence of both a dilution (distance effect) and deposition. Noise and air pollution (NO2 and PAH) levels were strongly correlated. Comparison of noise levels BLE and ALE also showed that the presence of leaves significantly reduced noise levels. Our results are evidence that urban green spaces are beneficial for urban environmental quality, which is important to consider in urban planning.
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| 10. |
- Mills, Gina, 1959, et al.
(författare)
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Closing the global ozone yield gap: Quantification and cobenefits for multistress tolerance
- 2018
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 24:10, s. 4869-4893
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Tidskriftsartikel (refereegranskat)abstract
- Increasing both crop productivity and the tolerance of crops to abiotic and biotic stresses is a major challenge for global food security in our rapidly changing climate. For the first time, we show how the spatial variation and severity of tropospheric ozone effects on yield compare with effects of other stresses on a global scale, and discuss mitigating actions against the negative effects of ozone. We show that the sensitivity to ozone declines in the order soybean>wheat>maize>rice, with genotypic variation in response being most pronounced for soybean and rice. Based on stomatal uptake, we estimate that ozone (mean of 2010–2012) reduces global yield annually by 12.4%, 7.1%, 4.4% and 6.1% for soybean, wheat, rice and maize, respectively (the “ozone yield gaps”), adding up to 227Tg of lost yield. Our modelling shows that the highest ozone-induced production losses for soybean are in North and South America whilst for wheat they are in India and China, for rice in parts of India, Bangladesh, China and Indonesia, and for maize in China and the United States. Crucially, we also show that the same areas are often also at risk of high losses from pests and diseases, heat stress and to a lesser extent aridity and nutrient stress. In a solution-focussed analysis of these results, we provide a crop ideotype with tolerance of multiple stresses (including ozone) and describe how ozone effects could be included in crop breeding programmes. We also discuss altered crop management approaches that could be applied to reduce ozone impacts in the shorter term. Given the severity of ozone effects on staple food crops in areas of the world that are also challenged by other stresses, we recommend increased attention to the benefits that could be gained from addressing the ozone yield gap.
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